Target tracking typically comprises inferring an unobserved state vector of a target (for example a vector including a target's position and velocity) from a given set of sensor observations and prior assumptions about target behaviour and sensor properties.
Conventional multi-target tracking algorithms tend to encounter problems when implemented in certain situations. In particular, problems tend to be encountered in situations in which the motion of targets is constrained and the paths of targets overlap or are proximate to one another (e.g. road vehicle targets may be constrained to travel on roads, and a portion of a track followed by a target may be shared by multiple targets).